1. Field of the Invention
The present invention is directed to an articulated riser which extends from an underwater installation toward the water surface. The present invention is directed to an articulated riser which includes at least two framed structures comprised of a plurality of fluid-handling lines and multiple fluid-handling line flexible joints connected between the framed structures.
2. Prior Art
In the search for crude oil and natural gas in deeper and deeper waters, a need has arisen wherein large volumes of fluids can be transferred between subsea installations and the water surface. It becomes economically unfeasible to provide fixed platforms which extend above the water surface which can extend to the depths at which the search for crude oil and natural gas is now being carried out. One approach suggested for extending multiple fluid-handling lines from subsea installations to the surface in deep water production operations is to house the lines in a self-standing riser consisting of a long, slender column that may be pivoted at the bottom and buoyant at the top so as to extend upwardly from the subsea bottom toward the surface of the water. Such a riser when rigidly attached to a vessel at the water surface is subject to being overstressed from currents, vessel offset, or vessel motion. A need, therefore, exists for a riser that is flexible enough to tolerate the motions of the vessel on the water surface and that will withstand the loads imposed by deep water conditions.